Mr Johnson mistakenly told the Foreign Affairs Select Committee last week that Ms Zaghari​-Ratcliffe was "simply teaching people journalism" when she was detained by the Iranian authorities 18 months ago. Her family has insisted that she was actually in Iran on holiday at the time.

In the wake of his comments, the mother-of-one was hauled back before an Iranian court and warned her prison sentence could be doubled.

Critics have called on Theresa May to sack Mr Johnson - and PoliticsHome revealed last night how Shadow Foreign Secretary Emily Thornberry has urged Mr Johnson to resign if Mrs Zaghari-Ratcliffe's sentence is increased.

A Foreign Office spokesman said that during his call with Mr Zarif, Mr Johnson "expressed concern at the suggestion from the Iranian Judiciary High Council for Human Rights that his remarks last week at the Foreign Affairs Committee 'shed new light' on the case".

He added: "The Foreign Secretary said this was absolutely not true, it was clear as it always had been that Ms Zaghari​-Ratcliffe had been in Iran on holiday when she was arrested.

"The Foreign Secretary made clear that the point he had been seeking to make in his evidence was that he condemned the Iranian view that training journalists was a crime, not that he believed Iranian allegations that Ms Zaghari​-Ratcliffe had been engaged in such activity.

"The Foreign Secretary concluded by emphasising that his remarks could form no justifiable basis for further action in this case and urged the Iranian authorities to release Ms Zaghari​-Ratcliffe on humanitarian grounds. He set out his intention to visit Iran before the end of the year to discuss the case further."

He added: "The Foreign Secretary accepts that his remarks to the Foreign Affairs Committee could have been clearer on this aspect."

The spokesman insisted that Mr Zarif told Mr Johnson that his comments had played no part in Ms Zaghari​-Ratcliffe being hauled before a judge at the weekend "and that he remained committed to working with the Foreign Secretary to find a solution to the case on humanitarian grounds".